Preparation of hydrogel beads for drying



Patented June 23, 1953 PREPARATION OF HYDROGEL BEADS FOB DRYING HenryErickson, Calumet City, 111., assignor to Sinclair Refining Company, NewYork, N. Y., a corporation of Maine No Drawing. Application January28,1950, Serial No. 141,171

4 Claims. 1

This invention relates to improvements in manufacture of silica gel andsilica gel base cracking catalysts in bead form.

Bead form catalysts are particularly useful in bed type crackingprocesses of either the fixed bed or moving bed type. Silica gel beadsare useful in the manufacture of cracking catalysts by incorporation ofactive metal oxides such as alumina or magnesia and inadsorption-desorption processes. The bead .form is characterized byhomogeneity of structure and smooth spherical or spheroidal shape. As aconsequence the bead form is advantageous in fluid-solid contactingprocesses where the solid contact material is handled as a bed inparticle form. The bead form particles pack well to form a homogeneousbed which minimizes channeling of fluids and promotes uniformity incontacting. In catalytic cracking, uniformity of contacting is.important in terms of capacity and maximum conversion per pass and alsoin the regeneration cycle in terms of capacity and efficiency ofregeneration. The bead form also is easy to handle and has satisfactoryresistance to attrition. For example, bead form particles may be handledsatisfactorily by gas or vapor lift.

The manufacture. of silica gel and silica gel base particles in beadform is made difficult and expensive because the bead form particles areproduced as hydrogels which must be dried and thermally treated beforeuse, the bead form hydrogels being highly susceptible to splitting andfracturing during such drying. Consequently, it is generally understoodthat it is necessary to resort to expensive and complicated dryingexpedients to reduce breakage to'a tolerable amount.

For example, it is necessary to use equipment adapted'to ciosecdntrtrtna commercial scale that permits a closer controland gradual temperaturerise over-the drying cycle. Another expedient is illustrated in .Payne'Patent No.

2,472,776 which describes drying at-100 per cent-- relative humidity andconstantlyincrasing item: I .l'

peratures. i p

I have found that breakageof silica gel and silica gel base duringdrying may be reduced to a very low quantity if the bead form hydrogelis treated before drying with an aqueous solution of a surface activeagent; According tomy invention the bead form hydrogel is treated bywashing or slurryingin an aqueous medium containing a small amountnotexceeding about 1.0 weight per cent of the surface active agent. Thetreated bead form' hydrogel. then may be. subjected t ordinary constantoven temperature drying or to controlled temperature rise drying at highrates with only a small amount of breakage occurring.

In my co-pending applications Serial Nos. 141,169 and 141,170, bothfiled of even date herewith, I have described treatment of silica-gelmetal oxide cracking catalysts with small amounts of surface tensionreducing agents in order to improve porosity and permeability of thecatalyst structure and to improve product distribution resulting fromthe use of the treated catalysts in hydrocarbon processes. In treatingbead form hydrogels. however, the improvement in breakage does notappear to be the result of I the surface tension reducing function'ofthe surface agents but appears to result in the capacity of the surfaceactive agent to form a colloidal film over the surface which ispermeable to water vapor so that water evaporation is slowed down butnot prevented. In some instances porosity is improved by the treatmentand this improvement may be due to surface tension reduction. Breakageof homogeneous beads in drying then is probably prevented by thecontrolled evaporation rate such that the surface does not dry muchfaster than the interior portion of the beads. Of course, thisexplanation is based upon theoretical considerations only, and myinvention does not depend upon its accuracy. I have found, however, thatmaterials of low surface tension such as oil and alcohols appear to becompletely ineffective in reducing breakage in drying and indeed incertain instances promote breakage. Also, I have found that too much ofthe surface active agent must not be used in treatment according to myinvention or the improved resistance to breakage in drying is entirelylost. The upper limit in terms of concentration of the agent in waterusing the minimumamount of water to obtain a completely ffluid Slurryappears to be about 1.0 weight per cent. The amount of agent necessaryfor improvement depends in general upon the nature of the agent and thesolids content of the hydrogel. Ordinarily about 0.1 to 0.5 weight percent :is sufficient. The concentration of agent .used is based on thetotal water, including that contained in the hydrogel. Where thehydrogel contains about 90% water for example, the concentration basedon solids may be obtained by multiplying by a factor of nine.

The useful agents are surface active agents whose molecules contain botha hydrophobic portion and a hydrophilic portion such as a soap ordetergent. A wide variety of surface active 3 materials is known in theart. See for example the classification and description of commerciallyknown surface active agents by John W. Mc- Cutcheon Chemical Industriesvol. 61, 811-822,

4 gel is first treated so as to incorporate a small amount of surfaceactive agent. For example, at the conclusion of the washing step, thebead form hydrogel is contacted with an aqueous solu- November 1947. Theuseful materials include, 5 tion of the surface active agent. Adsorptionfor example alkyl aryl sulfonates and sulfonic ordinarily is incompleteso that the excess soluacids, sulfonated' alkyl succinates, sulfatedfatty tion drained from the hydrogel may be recycled alcohols, fattyesters of polyhydroxy alcohols, to obtain maximum utilization of surfaceactive condensation products of ethylene oxide and fatty agent. acidsand the like. The cationic detergents such The effectiveness oftreatment according to as the quaternary ammonium compounds also myinvention is illustrated in the following exappear useful although theyare more expensive amples: at the present time. Example I Many of theuseful detergents contain a me- 7 tallic ingredient which is undesirablein finished Silica y l in b ad form Was Washed fr cracking catalysts gsodium which tends t of sodium and sulfate ions with dilute sulfuricpromote sintering and loss of area of silica gel acid and demineralizedWater- A Sample Of the catalysts. I have found that these materialsbeads was p aced o an even at C-, dried may be improved for useaccording to my inven- L fOI 24 hOllIS and calcined for 3 1101115 at1350 F. tion by exchange reaction with metals such as 2;) The furnace ptu was raised a ap d y magnesium orradicals such as ammonium which aPossible from rO p u e to 135 F. are not harmful and which actuallycontribute in about /4 heur- Every b ad Was ther Comto activity as inthe case of magnesium. In adpletely Shattered SO badly fi u ed as to bedition to the commoner. soaps, I have found useless- The pp density of eP u that ammonium soaps of higher fatty acids, e. g. 25 was ammonium m rt and t ni oaps A second sample of the beads, was treated with of mixedfatty acids derived by oxidation of Water c nta ning 0.1 p cent o erosol0S waxes, are valuable in the process or" my inven- (isoprepyl p le esodium sulfonate) but 11 11, A i t of t agents nay be used if otherwisein an identical manner. Of 148 beads d i examined only one was fissured.01" ten beads As indicated abovefsilica gel beadsuseful in tested, 3 hada Crushing Strength f 55 1 011 adsorption processes may be profitablytreated one Of 70 pounds nd t e balance of over 30 according to myinvention. Mixed gels, hoW- pounds- The apparent d n ity was 0.47. It isever, of the type commonly employed in catalytic probable that thisSlight difielehee in density cracking processes in the petroleumindustry are due to the 010861 peeking 0f he S a tered treated withparticular advantage. Thus bead beadsform silica alumina hydrogel,silica magnesia Example II hydrogel or silica gel base catalystscontaining 7 mixtures of alumina and magnesia or other aclu a hydrogelin bead form was tive ingredients such as. zirconia or titania are 40treated m a manner Similar to Example I With illustrative. The silicagel base catalyst may be and Wlthout a per Cent Solution of AETOSOIprepared by co precipitation methods, by OS (isopropyl naphthalenesodium sulfonate). pregnafion of preformed silica hydrogel beads Withthe untreated sample, breakage upon heat or by incorporation of themetal oxide ingreditreatment amounted to 93 P cent With the ents infinely divided form into the silica sol. sample treated with the surfaceatctwe agent,

The materials are ordinarily prepared in bead breakage was reduced to 5per centform by dropping particles of the sol or partially formed gelthrough a column of oil. The Example HI recovered spherical particles orbeads of hydro- In the following tests, the washed hydrogels gel arewashed free from inorganic materials in bead form were treated withvarying surface and then are hardened by drying and finally are activeagents in varying amounts and then dried. activated by calcination byhigh temperatures. The results are tabulated below together withAccording to my invention the bead form hydrocontrol tests on blanksamples:

C 1m -ii g f H Percent Percent D l 't' ler .t eat Treatment wholeBreakage s o Percmt N pitt'fiilt c i 331i "at 86.0 7

'1 -.do..- 2 -o.1 do afir gel. 87.1 III II" Dried at C- 22.0 '75" -o.1-...do 82.6 51 56.7 35, 87.0 0 38.2 56, 32.8 62, do 12. I s;o,=ao,.saddest-state's: 2919 s 5: SlOz2A1zO: 0.1 O-L 80.8 7

SlO2ZA1203.- 0.1 Dried at 110C 70.0 12'.

- Aerosol OS (isopropyl naphthalene sodium sulfonate). b Ammoniumlaurate. golecyl benzeng magnelsilnm snll'onate.

o 111111 53 o accona SA alkyl aryl sodium sulfona 9 Gl m (diamyl phenolethylene oxide polymer). te)

Example IV In the following treatments, 200 grams of the hydrogel inbead form were covered with 100 ml. of a solution of various agents. Thesamples were drained, dried at 110 C. and calcined for 2 hours at 1050F. The calcined beads were separated and the whole and broken beadsweighed. The percentage breakage is based on the difference in theweight percent broken beads in each sample as compared to that of theoriginal hydrogel. The results at diirering concentrations for differentagents follow. The original hydrogel 7 contains 87.1% Whole beads.

Percent Percent Percent A ent g Agent mag: Breakage None 22. 75. 0Aerosol OT 0.01 55.0 25.4 D 0. l 83. 0 4. Do 0. 3 87. 7 0. 0 O. 5 84. 13. 4 1. o 60. 0 31. 1 Glim 2 0. 01 62. 9 27. 8 D 0. 1 90. 6 0. 0 0. 388. 2 0. 0 0. 5 78. 6' 9. 8 Do 1. 0 62. 0 28. 8 Igepal CA 3 0. 01 33.162.0 D 0. 1 59. 7 31. 4 0. 3 63. 0 25. 4 0. 5 90. 7 0. 0 1. 0 70. 0 l9.6

1 Dioctyl sodium sulfosuecinate. 1 Diamyl phenol ethoxy polymer. 3Paraisoctyl ethow polymer.

Example V The silica alumina bead of Example IV after treatment with 0.1weight percent of Glim (diamyl phenol ethoxy polymer) was dried,calcined and the effect on pore radius was determined by conventionalnitrogen isotherm proced- I claim:

1. In the preparation of bead form silica gel base cracking catalystselected from the group consisting of silica alumina and silicamagnesia, the step of treating the bead form hydrogel before drying withan aqueous solution containing from 0.1 to 0.5 weight per cent of asurface active agent based on total water content, the said surfaceactive agent being selected from the group consisting of alkyl arylsulfonates and sulfonated alkyl succinates.

2. The method of preparing bead form silica gel base cracking catalystselected from the group consisting of silica alumina and silica magnesiafor drying which comprises treating the bead form hydrogel with anaqueous solution of 0.1 to 0.5 weight per cent of a surface active agentbased on total water content, the said surface active agent beingselected from the group consisting of alkyl aryl sulfonates andsulfonated alkyl succinates.

3. A method according to claim 1 in which the surface active agent is analkyl aryl sulfonate.

4. A method according to claim 1 in which the surface active agent isisopropyl naphthalene sodium sulfonate.

HENRY ERICKSON.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,455,843 Weir Dec. 7, 1948 2,459,903 Voorhees Jan. 25, 19492,490,260 Ehrhardt Dec. 6, 1949 2.532497 Hoekstra Dec. 5, 1950

1. IN THE PREPARATION OF BEAD FORM SILICA GEL BASE CRACKING CATALYSTSELECTED FROM THE GROUP CONSISTING OF SILICA ALUMINA AND SILICAMAGNESIA, THE STEP OF TREATING THE BEAD FORM HYDROGEL BEFORE DRYING WITHAN AQUEOUS SOLUTION CONTAINING FROM 0.1 TO 0.5 WEIGHT PER CENT OF ASURFACE ACTIVE AGENT BASED ON TOTAL WATER CONTENT, THE SAID SURFACEACTIVE AGENT BEING SELECTED FROM THE GROUP CONSISTING OF ALKYL ARYLSULFONATES AND SULFONATED ALKYL SUCCINATES.